Valve for steam-engines



which forms iinrnn srAingrArENr i onirica M. W. BALDWIN, `OF PHILADELPHIA, PENSYLVANIA.

g VALVE FOR STEAM-ENGINES. y l

Specification of Letters Patent No. 8,900, dated April 27', `1852.

To all whom 'it may concern: A

Be it known that I, MATTHIAS BALI)- wiN, ofthe city and county of Philadelphia and State of Pennsylvania, have invented certain `new and `useful Improvements in` Steam-Engines; and I do hereby declarel that the following is afull, clear,`and exactj description ofmy said invention, reference being had to the accompanying drawing, part of this specification, and in which- Figure l represents a longitudinal 1section of the steam cylinder and valves of a liori` zontal steam engine together with the crankl shaft and valve gear thereof, Figs. 2 and 3 are views in. section .showing the relative position of the valves `and piston at different portions ofthe stroke,".and Figs. 4C and 5 are views of modified forms of my valve mechanism.

In all engines, but particularly in loco-1 motive engines and others moving at high: velocities, it is. desirable that the valves which effect the admission and discharge o-f` steam from the steam cylinder should be.

suddenly opened to their full extent and as suddenly closed, and various attempts have from time to time been made by engineersl as in the ordinary manner to slide steam to` accomplish this result. 4

My invention and. improvement consists in arranging in "a suitable valve chest a into or out of the cylinder. This method of operating the valves is applicable to engines of all descriptions. The mechanism represented at Figs. 1,2, and 3 in the accompanying drawings, is well adapted to the steam cylinders of a locomotive engine. In

` these iigures, A the steam cylinder which is of the ordinary construction and is fitted with a piston and piston rod in the usual manner; B is the connecting rod which imA parts motion from thefpiston rod to the crank C secured to the crank shaft. The

valves of this engine are contained ina valve chest D secured to the upper side of the steam cylinder and are two in number. `The lower valve E regulates the admission and discharge of steam to and from the i steam cylinder, and is moved directly by steam from the boiler whenever thefpiston `nears either extremity ofthe steamlcylinder.

The upper valve Gr, which slides upon the lower, regulates the flow of steam from the boiler to actuate the lower valve and is also constructed in such manner that it cuts of the supply of steam to the steam cylinder when the piston has` accomplished a part of its stroke, thus permitting the steam in the cylinder to act expansively. The lower or main steam valve has the form of a' rectangular block and slides upon a seat, secured' to the upper side of the steam ,cylinder..v This seat is pierced with two steam ports a, Zn, and with an exhaust port, o. The former communicates by means of the steam passages d, d withwtlie extremities ofthe cylinder to which they are respectively adjacent. The exhaust port o communicates withthe exhaust passage I-I, by which the spent steam is conducted to the `exhaust pipe. The lower face of themain steam valve is pierced with two steam ,passages e, f and with'a cavity g, which forms the communication between `the exhaust port and the steam port of that extremity of the cylinder from which the steam is exhausting.. The steam passages e, f are extended through the valve and terminate in ports at the upper face thereof. This steam valve is tted tight upon its seat on the cylinder. Its sides are also littedf to slide steam tight against the adjacent sides of the steam chest or steam packing is inserted between the two, so that the steam valve constitutes a species of piston by which the one extremity of the valve chest is separated from the other.` The upper valve G has also the form of a rectangular block. Its lower `face vslides `upon the upper face of the main steamvalve beneath. One of its sides is iitted to slide steam tight against the adjacent side, 7L, of the valve chest, and its opposite side 1s either fitted to slide steam tight against the adjacent side of the steam chest, or steam packing is inserted between the two, anditsupper face slides steam tight against the lower face of a self adjusting ajutage J, which is inserted through thetop, la, of the valve chest, its sides being packed to prevent the passage of steam to the valve chest otherwise than through the ajutage.

` The upper valve Gr is pierced with `a passage m which extends transversely through it, and terminates in ports in its upper and lower faces respectively. As this valve is lOO 40 .v v`fore the latter arrives at the extremity of its stroke.

constructed to cut o the supply of steam from the boiler when the steam piston has accomplished only a portion of its stroke, the port in the lower face of the valve is of about the same dimensions as the ports in the up-per face of the main valve beneath. The object of the upper port in the upper valve is to forma communication between each extremity of the valve chest, and the ajutage, J, in alternate succession. This port therefore is of such width that as the Lipper valve nears each extremity of its stroke the outer edge of the port passes beyond the Aouter edge of the lower face of the ajut-age, as shown at Fig. l, thus per-` mitting the steam from the ajutage to passv kto that extremity o f the valve chest toward -which the valve is` moving aty the time.

That side face, L, of the valve'chest against which the upper valve slides is pierced with two ports z', each of which `occupies such a position with respect to the adjacent extremity of the upper valve that when this valveis in a position to allow steam to pass by means of its upper port to one extremity of the valve chest thelateral port, z', of the opposite extremity of the valve chest is uncovered. These lateral ports communicate with the exhaust pipe by means of lateral Vpassages whose position is shown by red lines in Fig. l.

j The upper valve, G, is caused to move to and fro by means of an eccentric L upon the crank shaft with which the valve is connected by means of a suitable rod n, arms '79, p, rock shaft 1, and valve stem s, and the eccentric is set at such an angle to the crank that the upper valve is moved to admit steam into that extremity of the valve chest toward which the piston is moving just belWhen therefore the engine is at work and the piston is moving in the direction indicated by the arrow, t, in Fig. 1, the upper valve is movedto the'position in which itis represented in this figure just before the piston reaches the extremity of its stroke. As the upper valve arrives at this position the port in its upper face permits steam to pass from the ajutage, J, into the extremity of t-he valve chest, while at the same time the lateral exhaust port, z', leading from the other extremity of the valve chest is uncovered. The steam entering the valve chest presses upon the head of the main steam valve as upon a piston, and as the pressure upon the opposite head of the valve is merely that of the exhaust passage, with which this extremity of the valve chest is in communication, through the lateral exhaust port, z', the main steam valve is forced with the whole pressure of the steam toward the opposite extremity, u, of the valve chest by which movementk its steam passage, f, is made to correspond inr position with the steam port, b, of the steam cylinder, while the cavity, g, in its lower surface at the same time forms a communication between the port, a, of the opposite extremity of the cylinder and the exhaust port c. -The piston and valve now occupy the positions in which they are respectively represented at Fig. 2,V hence the steam from the boiler passing through the ajutage J, the passage, m, in the upper valve and the steam passage, f, in the lower valve, enters the cylinder through the steam port, b, and the steam j passage appertaining thereto, and acts upon the head, of the piston, while such steam as may be in the cylinder at the opposite side of the piston. exhaust freely therefrom. As the piston begins to retrograde in the direction indicated by the arrow,`fv, the eccentric turning with the crank shaft moves the upper valve in the same directionas the piston, and as the main steam valve remains stationary during this movement of the upper valve the latter gradually passes over its upper face and in the example here represented closes the upper port of the steam passage, f, when-the piston has accomplished half of its retrograde strokeA (the piston and' valves now occupying the positions in which they are respectively represented at Fig. 3) by which means the communication between the boiler and the steam in the cylinder is cut olf and the latter is permitted to act expansively upon the piston. As the piston continues to retrograde the upper valve is moved onward, and as the piston nears the extremity of its retrograde stroke, the upper valve is brought into a position to admit steam into the extremity of the valve' chest u, while by the same movement the lateral exhaust port e' leading from the opposite extremity, w, of the valve chest is uncovered.

'The steam from the boiler now forces the main steam valve to move in a direction the j reverse of that in which it moved during the preceding stroke of the piston, thev passage, e, is brought into correspondence with the port, cz,"of the cylinder from which steam has just been exhausting while the U cavity, g, in the lower face of the valve forms a communication between theY opposite port, ZJ, of the cylinder and the exhaust passage; hence a fresh quantity of steam from the boiler is admitted to act upon the head a, of the piston, while the steam on'the opposite side of the piston is permitted to exhaust freely as before. This new supply of steam from the boiler is cut off in the same manner as that supplied during the preceding stroke of the piston by the covering of the passage in the lower valve by the face of the upper valve as the latter is moved by its eccentric toward the opposite extremity of the valve chest.

From the above description it is clear that the main steam valve is moved at intervals,

and that the movements occur whenever the piston reaches either extremity of its stroke;

instantaneously. The movement of the valve in each direction is limited by a spring bumper, y, afxed to the inner face of the valve chest, whose elasticity breaks the force of the blow or concussion caused by the sudden stoppage of the valve.

Instead of employing the bumpers y to deaden or break the concussion produced by the sudden stoppage of the valve, a quantity of steam or air may be employed for the purpose by inclosing the same in a recess at the end of the valve, so that it will be compressed as the valve nears the end of its stroke and by its resistance to compression will lessen or break the concussion.

In the engine, portions of which are represented at Figd, the arrangement of the valvesis somewhat different from the foregoing. The lower valve E as shown in this figure is fitted to move in a cavity formed in the lower face of the upper valve, G, whose construction does not vary materially from that of the ordinary short slide valve. One of the sides of the inner valve is fitted to slide steam tight against the inner face of the adjacent side of the outer valve. The spaces between the opposite side and the top of the inner valve and the adjacent inner faces of the outer valve are packed as shown atc in the drawing. The cavity of the outer valve therefore acts as a valve chest within which the inner valve is moved to and fro like a piston by the pressure of steam alternately upon its opposite extremities. The exhaust of the steam alternately from each extremity of this cavity is effected through ports z', i, which communicate with passages in the o-uter valves that conduct the steam to the exhausting cavity, g, of the inner valve. The admission of steam alternately to theopposite extremities of the inner valve is effected by making the covering portions, Z, Z, of the outer valve of less width than the ports, a, b, over which they move, hence whenever the upper valve begins to open either steam port, theisteam passe-s around beneath the covering part of the valve and enters the adjacent extremity of the cavity or steam chest within which the inner valve is contained as shown by the arrow, g, in the drawing.

The valve gear I have thus far described is arranged to work when the piston is driving the crank shaft in one direction. They be fitted to work equally well whenthe movement of the crank shaftis to be reversed by reversing the movement of the upper valve either `by means of a second eccentric aflixed to the crank shaft at a suitable angle with the crank, as represented in red lines in Fig. 4, or in any other of the well known methods in use for reversing the valves of steam engines. The last arrangement of valves is adapted only to the sudden opening of the exhaust, as the admission of steam is regulated wholly by the upper valve, but this arrangement of valve may be modified to effect the sudden admission of steam also, by extending the face of the lower valve at each extremity beneath the extremities of the upper valve, so that the upper faces of these extended portions of the lower valve form seats on which thel extremities of the upper valve slide. Suitable ports must also be made in these faces to permit the steam to pass into either extremity of the cavity of the upper valve when the lower valve is to be moved. The upper valve in this case as well as in that first described may be made to effect the cutting-0H of the steam by forming passages in the lower valve which will be covered at the pro-per moment by covering portions of the upper valve.

What I claim as my invention and desire to secure by Letters Patent, is-

The arrangement in the valve chest of a steam engine, of a duplex valve one part of which is actuated in the usual manner by valve gear to admit steam from the boiler to act directly on the other part and force it to open and close the steam or exhaust passages, substantially as herein described. In testimony whereof I have hereunto subscribed my name.

MATTHIAS W. BALDWIN. Witnesses:

L. REGNAULT, J oHN A. WHITE. 

